In a semiconductor process, for example, in order to secure depth of focus (DOF) of lithography, it is desired that the surface of a to-be-processed object has high flatness.
Although there is a chemical mechanical polishing (CMP) technology as a processing technology for planarization, polishing damage (scratches) caused by abrasive grains (physical polishing agent) in a slurry to be used provides cause of yield reduction.
As a polishing method using no physical polishing agent, there is a method in which an ice layer embedding a concave-convex face therein is formed and the concave-convex face is polished while dissolving the ice layer from its surface. Furthermore, there is also a method for polishing a substrate, in which CMP polishing agent containing an insulating film-dissolving agent, an insulating-film-dissolution-protecting agent, and water therein is used, and in which the surface of a substrate is polished while preventing etching of a to-be-polished film and weakening the surface of the to-be-polished film during CMP polishing.